PyDev 3.1.0 is now already available for download.
The debugger got a lot of attention in this release:
One of my favorite features is the code reloading. This means that when you change a file in the PyDev editor and there's a debug session going on, PyDev will automatically reload that module.
There are some caveats on doing that:
1. It'll try to reload the objects code in place (without changing references), but the code you're currently using in a frame in the current stack cannot be changed, so, you'll have to get out of the function and then back to see the changes (the set next line feature in the debugger which allows you to set the next line to be executed in the current scope can be very helpful for that).
2. Not everything can be cleanly reloaded (see: https://github.com/fabioz/Pydev/blob/development/plugins/org.python.pydev/pysrc/pydevd_reload.py for the limitations on xreload).
Still, it's very nice that you can now do the reload and it does work well on many situations ;)
Another nice thing is that it's now possible to inspect which are the referrers of a given variable by right-clicking it on the variables or expressions view and selecting 'get referrers'.
One last thing I'd like to mention is that Stackless Python is now supported in the debugger, which will show the tasklets as if they were threads in the stack view.
Besides the debugger, the rename refactoring also got some love, so, it's now possible to rename a module/package having all references updated as well. Also, the find references (Ctrl+Shift+G) had some bugfixes and should be more reliable now.
There are still a number of other nice things, so, check the release details on http://pydev.org for more information.
p.s.: Note that PyDev requires Eclipse 3.8 onwards and Java 7 (for older versions, keep using PyDev 2.x)
p.s.2: LiClipse (http://brainwy.github.io/liclipse/) is recommended for users that want a PyDev standalone with a hassle free install where things should 'just work' (also, by licensing LiClipse you directly support the development of PyDev).